Toluenediisocyanates, otherwise referred to herein as TDI have become an important component in the preparation of various commercially useful products including but not limited to, polyurethane foams, elastomers and coatings. However, as a results of the production of toluenediisocyanates, waste in the form of toluenediisocyanate residues, sometimes referred to as distillation bottoms, are generated.
In view of the extensive production of toluenediisocyanate world wide and in turn, the generation of high quantities of toluenediisocyanate residues, the need for a reliable process for recycling toluenediisocyanate residues and recovering the useful products generated as a result is readily apparent.
While alternative processes can be employed to recycle toluenediisocyanate residues into useful products, it is believed that the present invention offers the most convenient and cost effective alternative available to date. For example, it is possible to recover many of the aforementioned products from toluenediisocyanate residues by reacting the residue with an excess amount of an alcohol such as ethanol, propanol, butanol, pentanol and cyclopentanol, among others. However, in order to drive the reaction, the residue must be heated to a temperature of approximately 200.degree. C. As a result of the reaction, an extensive amount of carbon dioxide is generated, thus, the reaction must be carried out in a pressure vessel capable of handling pressures of up to 400 lbs/in.sup.2. In contrast, the process of the present invention does not generate any carbon dioxide, or other such gases and therefore, can be carried out at relatively low pressures.